1. Field of the Invention
The subject invention relates to stacking methods and apparatus and, more specifically, to methods and apparatus for stacking papers, documents, cards and other sheets of various intermixed lengths, thicknesses and other characteristics.
2. Disclosure Statement
The following disclosure statement is made pursuant to the duty of disclosure imposed by law and formulated in 37 CFR 1.56(a). No representation is hereby made that information thus disclosed in fact constitutes prior art, inasmuch as 37 CFR 1.56(a) relies on a materiality concept which depends on uncertain and inevitably subjective elements of substantial likelihood and reasonableness and inasmuch as a growing attitude appears to require citation of material which might lead to a discovery of pertinent material though not necessarily being of itself pertinent. Also, the following comments contain conclusions and observations which have only been drawn or become apparent after conception of the subject invention or which contrast the subject invention or its merits against the background of developments which may be subsequent in time or priority.
There is an increasing demand for methods and apparatus for stacking various documents, papers and other sheets rapidly and reliably, without paper jams and other disturbances.
To a large extent, this demand has been sparked by the desire of public utilities, banks and other institutions to economize, automate and speed up the processing of payments by customers. In practice, the resulting advanced remittance processing systems require high-speed stackers capable of handling such items as bank checks and remittance stubs of various intermixed lengths, thicknesses, formats, textures and surface finishes. Such stackers are to be capable of stacking received documents or sheets in their original sequential order in which they were fed into the stacking apparatus or system.
For a relatively early card sorting machine, reference may be had to U.S. Pat. No. 2,020,925, by D. A. Young, issued Nov. 12, 1935. In such early machines, cards were fed into the stack from the bottom thereof with the aid of card holders, dogs and cams.
Reference may also be had to U.S. Pat. No. 3,132,231, by J. F. Dunser, issued Oct. 4, 1938 and disclosing apparatus for sorting flexible sheet material, U.S. Pat. No. 2,626,800, by G. A. Martin, issued Jan. 27, 1953 and disclosing sheet delivering apparatus, U.S. Pat. No. 2,771,293, by E. J. Guttridge, issued Nov. 20, 1956, and disclosing record card controlled statistical machines, U.S. Pat. No. 2,822,717, by G. A. Luning, issued Feb. 4, 1958 and disclosing a stacker arrangement in which roller combinations cause cards to snap into a stacking position, U.S. Pat. No. 2,933,313, by A. R. Stobb, issued Apr. 19, 1960, and disclosing methods and apparatus for collecting flexible sheets, U.S. Pat. No. 2,970,836, by J. G. Smith, issued Feb. 7, 1961 and disclosing stackers in which sheets are blown into the stacking location, U.S. Pat. No. 3,079,151, by E. P. Maidment, issued Feb. 26, 1963 and disclosing a document handling stacking apparatus, U.S. Pat. No. 3,994,487, by H. P. Wicklund, issued Nov. 30, 1976 and disclosing a sheet handling apparatus for stacking burst sheets with the aid of roller mechanisms, and U.S. Pat. No. 4,067,568, by R. Irvine, issued Jan. 10, 1978 and disclosing stacking apparatus in which items, such as envelopes, are fed into a stacking location from below with the aid of a planetary roller assembly. Most of these existing proposals depend on certain given sheet or item dimensions for their proper operation. The proposal according to U.S. Pat. No. 3,148,879, by H. J. Kistner, issued Sept. 15, 1964, attempts to strike a certain compromise by providing a stacking apparatus with a length adjustment facility. In this manner, it appears possible for the stacking apparatus to handle one length of sheets at one time, and another length of sheets at another time. However, this still does not permit a stacking of sheets at variously intermixed lengths. Also, that proposal employed a leaf spring for driving advancing sheets into the stack, thereby introducing an inherent speed dependency. Moreover, that proposal required oscillating pushers for placing the sheets into the stack.
A more recent type of document stacking apparatus, illustrated in U.S. Pat. No. 4,241,909, by Murphy et al, issued Dec. 30, 1980 employs a gravity-bias principle in conjunction with a power drive roller having an elastomeric serrated extended diameter cap, and a roller mechanism, rotatable in a direction counter to that which would normally feed documents along a predetermined path, for retarding the movement of the documents and facilitating their stacked arrangement within the stacking cavity. In this respect, the embodiment illustrated in the latter patent shows a support roller having a pair of smaller rollers mounted thereon for retarding advancing documents to a proper extent for stacking within the apparatus. In a commercial version of that type of stacker, a reversely rotating square-shaped elastomeric member is employed in lieu of the latter illustrated document retarding roller mechanism.
In practice, gravity-bias systems are not universally applicable. Also, the use of elastomeric serrated roller caps or square-shaped roller members may impose noticeable vibration on the stacking apparatus and entail accelerated wear.